Electrical multi-contact devices



Oct l1, `1960 w. J. PADDocK ELECTRICAL MULTI-CONTACT Drsvrcss Filed April 24, 1957 inganni s ELECTRICAL MULTI-CONTACT DEVICES William Joseph Paddock, Pattingham, England, assignor i to Ega Electric Limited, We'dnesbury, England, a British company Filed Apr. 24, 1957, Ser. No. 654,695

'Claims priority, application Great Britain Oct. 19, 1956 1 Claim. (Cl. 200-166) 'Ihis invention relates to electrical multi-contact devices embodying an assembly of contact elements or contact-carrying elements, and it has especial reference to multi-contact plu-g and socket connecting devices and to multi-contact electric switches, the latter being of the kind comprising a plurality of spring or resilient metal blades or fingers which carry electrical contact points and which, together with associated insulation pieces, are assembled in superimposed rela-tion in the form of a stack or pile. Such multi-contact switches are frequently used in conjunction electro-magnetic devices in relay circuits, and also in the construction of thermostats and like heat-sensitive control arrangements, as well as for manual control switches or keys.

The object of'th'e invention is =to provide an improved construction of' such multi-contact devices whereby the assembly of the contact elements or contact-carrying elements is facilitated.

In the case of multi-contact switches of the kind refer-red to, the contact-carrying fingers and their associated insulation pieces have, heretofore, been assembled in a stack or pile which has been clamped together by clamping-screwspassing therethro-ugh. This known construction has required that the lingers and insulation pieces be' drilled to form screw-receiving holes, and has also had the disadvantage that should any individual finger need to be removed for repairor replacement, the whole stack or pile has had to be taken apart `to enable' the finger to be withdrawn'.

Accordingly, another object of the invention is to provide a multi-contact switch, of the kind referred to, having improved means for mounting and clamping the contact-carrying fingers and the insulation pieces in assembled relationship, whereby the necessity for drilling screwreceiving holes therein is obviated and whereby -any individual finger can be Withdrawn and replaced without disturbing the remainder of the stack or pile and external wiring associated therewith.

According to the invention, an electrical multi-contact device comprises a plurality of metallic or metallised contact elements, or metallic or metallised contact-carrying elements, and `associated insulation pieces assembled in superimposed relation in the form of a stack or pile within a housing, and means are provided whereby said contact elements and insulati-on pieces may be clamped together within said housing.

Also, according to the invention, a multiecontact switch of the kind referred to, has the contact-carrying fingers and associated insulation pieces assembled in the form of a pile or stack which is contained within a housing and clamped together therein by pressure means.

Several embodiments of the invention are illustrated, by way of example, in the accompanying drawings in which:

Figure l is a side elevation of a multi-contact manually operated key switch constructed in accordance with the invention.

Patented Oct. 11, 1960 ICC Figure 2 is a vertical cross-section on line II-II, Figure 1 but on a larger scale than that of Fig. l.

Figure 3 is a longitudinal part-section through the housing on line III-III, Figure 2.

Figure 4 is a horizontal section on line IV-IV, Figure 3.

Figure 5 is a perspective view of some of the contact elements and associated insulation pieces before assembly of the switch.

Figure 6 is a cross-sectional view similar to Figure 2 but showing a modified housing formed of plastic.

Figure 7 is a perspective View of a further form of housing.

Figures 8 and 9 illustrate modified forms of housing which may be used.

Referring to Figures 1 to 5 of the drawings, .the multicontact key switch comprises a plurality of resilient flexible metal strips or fingers 1 arranged in a superimposed and vertically-spaced relationship and carrying contact points 2 at their outer ends. The inner ends of the metal strips or fingers 1 are separated by insulation pieces 3 consisting of thin, substantially rectangular, plates or wafers of insulating material such as fibre or plastic, and in addition, in the form illustrated the inner end of each metal strip or finger 1 is in contact with a short meta-l terminal plate or strip 4, a portion of which is interposed between said inner end and an adjacent insulation piece 3. This assembly of the inner ends of the metal strips or fingers 1, insulation pieces 3 and terminal plates 4 in superimposed relationship forms a parallel-sided stack or Ipile indicated generally by the reference numeral 5, the elements of which are clamped together, in a manner hereinafter described, to maintain the individu-al members securely in place.

This stack or pile 5 is accommodated within a short rectangular-sectioned metal tube or openended hollow box-like member, which forms a housing 6, the interior side wall-s of which fit closely against lthe sides of the stack or pile 5 (see Figure 2). The vertical depth between the top and bottom interior faces of the housing 6, however, is greater than the vertical depth or height of the stack or pile 5, and the top side of -the housing is formed with tapped holes 7, 7, through which are passed clamping set-screws 8, 8. On the top of the stack or pile 5 and contained within the housing 6, beneath the top :side of the latter is a metal pressure or squash plate 9 which is pressed downwards by the'lower end of the clam-ping setiscrews 8, 8, so as to clamp the stack or pile 5 between said pressure or squash plate 9' and the bottom interior face of the housing 6.

The met-al terminal plates or strips 4 associated with each contact-carrying finger 1 of the switch are arranged to as ,to project trom the stack or pile 5 adjacent the one open end of the housing 6 whilst the contact-carrying fingers 1 project from the stack or pile adjacent the other open end of the housing. The individual fingers 1 are adapted to be connected into the circuit in which the switch is to be incorporated by wires 10 connected to the projecting portions `of their associated terminal plates or strips 4.

To prevent contact of two or more of the contactcarrying fingers 1 with the sides of the metal housing 6, which would result in a short circuit between such fingers, the inside of the housing may conveniently be coated with a layer of an insulating material indicated at 11. Alternatively plates of insulating material may be placed against the interior faces of the side walls of the housing v 6 for the same purpose.

metal mountingplate or bracket 13 a portion of which is included in the clamped stack or pile within the housing 6.

The main base 12 of the switch is formed with an integral fr ontbracket arm 14 upon which is pivotally mounted the usual operating lever 15 carrying a roller 16 for engaging and deilecting the outer ends of the contactcarrying iingers 1. K

It will be understood that the above-described construction of the switch unit readily allows any individual contact-carrying nger 1 to be removed Vby slackening the set-screws 8, '8, holding the pressure or squash plate 9, and then withdrawing the iinger lengthwise from the stack or pile 5. To facilitate this operation, and to avoidl disturbing the adjacent insulating pieces 3, the latter are illustrated as being substantially T-shaped, having shoulders 17 (see Figure-5) which engage the end edges of the housing when the stack or pile is assembled and prevent lengthwise movement, and the width of the central body part conforming closely to the horizontal width between the opposed interior side walls of the housing 6. The insulation pieces may also be I-shaped with shoulders at both ends. In withdrawing a rfinger 1 from the stack or pile 5, it will be understood that there is no need to disturb any of the associated wiring when the separate terminal plates or strips 4 are used as described. If desired, however, the contact-carrying fingers 1 may carry integral extension parts to which the associated wiring is connected as in known constructions of such multicontact switches.

Figure 6 illustrates a modilication in which the tubular housing indicated now by the reference numeral 18, is formed of insulating material such as a plastic, instead of metal. In this case, it is preferable to carry the clamping set-screws 8 in threaded holes 19 in a separate metal plate 20 interposed between the pressure or squash plate 9 and the top interior face of the housing, holes 21 being provided in the latter to allow the heads of the setscrews 8 to be accessible.

Figure 7 illustrates a plastic housing the lower part of which has longitudinal holes 22 for receiving fixing bolts so as to provide an alternative means of mounting upon a support.

The housing for containing the clamped stack or pile may be of other than tubular form if desired, being, for example, in the form of a U-shaped member as illustrated in Figure 8, arms 58 and 59 of the U forming the top and bottom faces, so as to permit of a sideways insertion of the elements of the stack or pile.

As shown in Figmre 9, the housing may also comprise an open framework structure embracing the stack or pile and pressure or squash plate 61. In the form illustrated, separate terminal plates 62 arranged to project from a side of the stack are provided and the insulation pieces (3) are of generally rectangular shape with incut corners fitting against the end bars 63 of the housing.

I claim:

An electrical multi-contact switch comprising a onepiece housing; a plurality 'of separate resilient contactcarrying ngers; a plurality of separate terminal conducting plates arranged adjacent to and in'electrical contact with said fingers and adapted to be connected to external wiring; arid a plurality of separate insulating plates associated with said ngers and terminal plates; all of said lingers, terminal plates and insulating plates being assembled in superimposed relation in the form of a stack within the housing with the fingers projecting from one side of the housing and the separate terminal plates in contact therewith projecting `from another side of the housing; and retractable clamping means external to said stack and operable from outside said housing whereby a controllable clamping pressure can be applied to the stack, said fingers and terminal plates and insulating plates being held together in operative position by frictional clamping pressure only exerted by said clamping means, said ingers being individually removable from said stack when releasing said clamping pressure.

References Cited in the iile of this patent UNITED STATES PATENTS 468,654 Gibbs Feb. 9, 1892 752,613 -Carliss Feb. 16, 1904 1,865,600 Welch July 5, 1932 1,917,009 Betts et al. July 4, 1933 2,025,380 Cruser Dec. 24, 1935 2,069,169 Leake Jan. 26, 1937 2,154,338 Knos Apr. 11, 1939 2,172,927 Andeen Sept. 12, 1939 2,277,443 Livingston Mar. 24, 1942 2,334,897 Baker Nov. 23, 1943 2,748,364 Kamm May 29, 1956 FOREIGN PATENTS 770,030 Great Britain Mar. 13, 1957 771,912 Great Britain Apr. 10, 1957 

